Deposition of wear resistant coatings based on diamond like carbon by unbalanced magnetron sputtering

Amorphous hydrogenerated carbon films containing a small amount of metal (Me:C-H) have been deposited by closed field unbalanced magnetron sputter ion plating. The films have graded film compositions to optimise the adhesion to the substrates, and multilayer TiC/Ti:C-H films have also been deposited. The films have excellent properties: very high measured microhardness (more than 4000 H_v), excellent adhesion (L_c 115–125 N), coefficients of friction against WC of less than 0.2, and volumetric wear rates one fifth that of titanium nitride. The coating procedure is ideally suited to the system used, and many applications for the films are already realised.     

金刚石-硬质合金复合片的耐磨性测试方法研究

金刚石-硬质合金复合片的耐磨性是一个非常重要的技术指标,但迄今为止国际上尚无统一的PDC耐磨性测试标准。本文在分析我国和乌克兰评价PDC耐磨性方法优缺点的基础上进行了对比性研究,指出乌克兰超硬材料研究所按复合片在实验台上切削岩块的磨损高度和面积来评价的方法,更接近于孔底岩石破碎过程,PDC的几何磨耗量可更全面真实地反映复合片在钻探生产中的工作寿命。同时,讨论了乌克兰方法需要完善的地方。     

金刚石锯片胎体的耐磨性

通过对４种胎体的锻切试验，研究了胎体耐磨性同胎体高温硬度的关系，提出了胎体高温软化的概念，并在测定胎体高温软化点的基础上，分析了胎体耐磨性同胎体高温软化点的关系。研究结果表明，胎体的高温软化点可以反映胎体耐磨性的好坏；对已知岩石的切割试验表明，在金刚石参数相同的条件下，选择成份合适的胎体可以使金刚石锯片的平均寿命提高２０－３０％。     

含氢类金刚石涂层在船用柴油机柱塞上的应用

利用磁控溅射和等离子增强化学气相沉积复合技术,以 Cr、WC、石墨为靶材,Ar和C₂H₂为工作气体,在船用低速柴油机柱塞上涂覆了过渡层依次为Cr、WC的含氢类金刚石涂层。结果表明:涂层晶体生长良好,结构连续致密,均未出现分层、开裂及剥离的现象;涂层相对光滑,大幅度提高了柱塞表面的纳米硬度与弹性模量,同时降低了在重柴油环境下的摩擦因数,长时间的台架试验后未涂覆涂层的柱塞表面出现非常明显的平行状沟槽磨痕,而且整体磨损比较严重,而涂覆涂层的柱塞表面磨痕非常窄且浅,数量较少,类金刚石涂层可以明显提高柱塞表面的耐磨损性能。     

Preparation of H-terminated and aminated diamond like carbon surfaces

H-terminated DLC layers were synthesized on SiO2 substrate by radio frequency (RF) magnetron plasma-enhanced chemical vapor deposition (PECVD) in a conventional reactor using C4H10 as carbon source. As-deposited DLC films were characterized by Raman spectroscopy, scanning electron microscopy (SEM) as well as atomic force microscopy (AFM). The chemical reactivity of the obtained DLC surface was further investigated by exposing the photochemically oxidized DLC surface to a silane reagent. The course of the reaction was followed using water contact angle and X-ray photoelectron spectroscopy.     

银基钎料钎焊金刚石耐磨性试验研究

本文采用添加Ti的Ag-Cu-Zn合金作为钎料,适当控制钎焊工艺,实现了金刚石与钢基体的高强度连接,采用扫描电镜和能谱仪对金刚石与钎料界面进行了分析,分析结果表明:Ti在界面处有聚积并与C生成化合物.为验证钎焊工具的性能,分别进行单颗磨粒磨损试验和套料钻钻孔试验,单颗磨粒磨损试验中,单颗磨粒在重负荷工作条件下,仍有正常磨耗的过程.套料钻钻500个孔时磨粒无明显磨损,说明采用添加Ti的Ag-Cu-Zn合金做钎料钎焊后,金刚石仍能保持良好的耐磨性能.     

选区电化学沉积镍镀层的微观形貌及耐磨性

利用选区电化学沉积技术在45钢基体上沉积镍镀层,并对其进行形貌观察、能谱分析探寻选区电化学沉积镍镀层组织生长规律,并将镀层和基体耐磨性进行了试验对比。结果表明,选区电化学沉积生长过程为由小型颗粒逐步生长堆叠成为致密镀层;晶粒生长呈螺旋式上升堆叠形态,球状晶粒内部和表面存在微裂纹;晶粒间隙处存在氧元素,氧化反应对于小型晶粒之间的相互融合起抑制作用;选区电化学沉积镍镀层结构组织更加致密,镀层组织与基体组织间存在明显的分界线,镀层组织相较于基体材料耐磨性更好。     

Antifriction and wear resistance of tin diffusion coating on brass

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Thermal stresses in diamond coatings and their influence on coating wear and failure

Thermal stresses in diamond coatings deposited onto cemented carbide substrates are calculated using the finite element method. The thermo-elastic stress fields for some coating-substrate geometries are presented. The results are compared with experimental data on the tribological behaviour of diamond coatings. Residual stresses can explain many of the observed patterns of coating wear and failure. A model for the abrasive wear of brittle coatings under large compressive biaxial stresses is described. These stresses prevent cracks initiated at the surface to propagate towards the interface and may promote crack paths parallel to the interface, thus causing the formation of a smooth coating surface. Once the smooth appearance is reached it will become extremely hard to initiate and propagate cracks into the coating and consequently the wear rate becomes very low. Thus, large compressive residual stresses increase the already high wear resistance of diamond coatings. When diamond coatings are deposited onto substrate edges, intense concentrations of normal and shear stresses may lead to coating failure by interfacial spalling. These stresses are lowered by increasing the ratio r/h, where r is the edge radius and h is the coating thickness.     

Analysis for the wear resistance anisotropy of diamond cutting tools in theory and experiment

In this work, the dynamic micro-mechanical strengths of diamond crystal are deduced in theory, including the tensile, shearing and compressive strengths. The calculated results reveal that the dynamic micro-mechanical strengths have great anisotropy, but the tensile strengths are less than the shearing and compressive ones in any orientation of any plane. Subsequently, a novel evaluation factor is proposed, which integrates from the theoretical tensile strength in the orientation of flank face paralleling to the cutting direction and the theoretical tensile strength in the orientation of rake face paralleling to the chip flowing direction. And then as expected, the anisotropy of the resistance to wear of diamond cutting tools can be predicted exactly through comparing the evaluation factor. Theoretical analyses indicate the larger the evaluation factor, the greater the wear resistance of diamond cutting tool is. Finally, the cutting experiments are carried out on the (1 1 1) silicon wafers, and the sampled data are well consistent with the theoretical predictions, which validates that the proposed evaluation factor is suited for predicting the anisotropy of the resistance to wear of diamond cutting tools.     

中锰高碳钢的冲击磨损性能及磨损机制

采用场发射扫描电镜(SEM)、MLD-10冲击实验机和硬度实验机等检测手段,对不同处理制度条件下的中锰高碳钢在中低冲击载荷条件下的耐磨性能与其磨损机制进行了研究。结果表明:低冲击载荷条件下,热轧态中锰高碳钢具有最优异的冲击磨损性能,远高于冷轧态与其他热处理制度下的中锰高碳钢,其磨损机制为剥削磨损与凿削磨损;在中等冲击载荷条件下,450℃保温15 min样品的冲击磨损性能最优越,且磨损机制为剥削磨损、凿削磨损与塑性变形。     

Thick tool steel coatings using HVOF spraying for wear resistance applications

This paper deals with the processing of thick cold work tool steel coating using high velocity oxy-fuel (HVOF) spraying process. A full factorial experimental design was established to identify the influencing process parameters on the formation of dense coating with low oxidation. Microstructural analysis of the coating was carried out using optical, SEM and XRD techniques. Cold work tool steel coatings with a thickness up to 2 mm were developed on bond coated low carbon steel substrates for wear resistance evaluation. A pin on disc test was performed to examine the wear resistance of thick cold work tool steel coatings on different types and sizes of abrasive papers. The wear results were compared with the wear resistance of a standard high speed steel pin. The abrasive wear resistance of cold work tool steel coated pins was found to be superior against soft and fine abrasive papers than the standard high speed steel. Besides, the performance of the coated pins against hard and coarser abrasive papers was found to be similar to standard high speed steel. The study showed the potential of HVOF spraying on the development of thick cold work tool steel coatings for wear resistance applications.     

Hard arc-sprayed coating with enhanced erosion and abrasion wear resistance

A cored wire formulation, referred to as Alpha 1800, has been developed to produce tailored arc-sprayed coatings that are tough enough to resist particle impacts at 90° and sufficiently hard to deflect eroding particles at low impact angles. One millimeter thick coatings composed of ductile and hard phases with a Knoop hardness reaching 1800 kg/mm² were easily produced by arc spraying the cored wire with air. Coatings were (1) erosion tested at 25 °C and higher temperatures at impact angles of 25 and 90° in a gasblast erosion rig, (2) slurry erosion tested at impact angles of 25 and 90°, and (3) abrasion wear tested using the ASTM G-65 test procedure. Results show that coatings produced with the new cored wire are at least 5 times more erosion resistant and 10 times more abrasion resistant than coatings produced by arc spraying commercial cored wires. The performance of the new arc-sprayed coating can be compared with that of high-energy WC-based coatings. Maintaining their erosion resistance after being exposed to temperatures up to 850 °C and possessing good oxidation resistance, arc-sprayed coatings produced with the new cored wire are attractive for applications in many industrial sectors involving high temperatures.     

非晶铝基粉末冷喷涂涂层及其耐磨性能

为提高镁合金的耐磨性能,采用冷喷涂技术在AZ91D镁合金表面制备铝基非晶涂层,并利用扫描电镜对涂层的微观形貌进行分析,采用X射线衍射仪分析喷涂粉末及涂层中的非晶含量,利用多功能摩擦磨损试验机研究了涂层的耐磨性能。结果表明:冷喷涂后涂层中仍含有铝基非晶结构,非晶含量为48%,涂层微观组织致密,孔隙率为0.59%。铝基非晶涂层的磨损量和磨损率均低于镁合金基体,摩擦因数高于基体。     

坡缕石对三元硼化物陶瓷涂层耐磨性的影响

三元硼化物陶瓷涂层由于硬度高、耐磨性好、热膨胀系数与Fe相近,是钢基体耐磨层的优选之一。坡缕石由于其独特的晶体结构,是减摩材料的良好选择。将占骨料总质量分数1%、2%、3%、4%、5%的坡缕石添加到三元硼化物陶瓷涂层中,测试了坡缕石对涂层耐磨性的影响。结果表明,坡缕石的添加使涂层变得致密,但对涂层界面强度影响较小;含2%坡缕石涂层抗磨粒磨损性能提高2.6倍,抗黏着磨损性能提高4.2倍。     

激光熔覆WC/Co-Cr合金涂层的组织及耐磨性

采用YAG固体激光器于45钢表面熔覆WC/Co-Cr合金涂层,对涂层的微观组织及界面结构进行了分析。探讨了不同WC添加量对涂层硬度及摩擦磨损性能的影响。结果表明,涂层主要由CrCo、WC以及W₂C相组成,还含有一定的Co的固溶体以及Cr₇C₃相。涂层微观组织呈大致等轴的细小网状共晶组织,涂层与基体呈冶金结合,表面硬度在1100 HV0.02左右。WC含量对涂层硬度以及磨损性能影响较大,呈显著的磨粒磨损机制。但当WC含量增加到20wt%以后,表面微裂纹增多,脆性增大,对使用寿命有不利影响。     

Improved microhardness and wear resistance of the as-deposited electroless Ni-P coating

The coatings with different phosphorus contents were obtained by varying the ratio of lactic acid to acetic acid in the electroless plating bath. With the increase of phosphorus content, the structure of the electroless Ni-P coating transformed from nanocrystalline to a mixture of nanocrystalline and amorphous phases, then to amorphous phase. A record high hardness value of 910 HV_0.1 of as-deposited Ni-P coating was obtained at 7.97 at.% phosphorus content, and high wear resistance was accordingly achieved. The refined nanocrystalline grains with an average size of ~ 4 nm were found to be responsible for the record high hardness and improved wear resistance of the as-deposited Ni-P coating.     

一种新型致密Fe基非晶涂层的制备与耐磨性能

采用活性燃烧高速燃气(AC-HAVF)喷涂技术在AISI 1045低碳钢基体上制备了一种新型Fe40Cu8Cr15Mo14C15B6Y2非晶合金涂层,通过XRD、SEM、摩擦磨损试验机等研究了涂层的微观结构及其摩擦磨损行为。研究表明,Fe40Cu8Cr15Mo14C15B6Y2涂层的厚度可达400μm,涂层基本由非晶相组成,且与基体结合良好,结构致密,孔隙率为1.2%。该Fe基非晶涂层具有较高的维氏硬度达1038 HV,极低的磨损量,约为基体AISI 1045低碳钢的1/4。在干摩擦条件下,涂层易发生层状剥落磨损。同时,摩擦界面的局部接触部位产生高的闪温,使涂层表面形成氧化膜,随着摩擦过程中氧化的不断进行,当氧化膜生长到某一临界厚度时,由于其本身脆性会最终破裂,形成氧化磨屑,进一步加剧涂层的磨损。     

Improvement of the wear resistance of Ti-based coating sliding against copper alloy

The multilayer coating, Ti10%-C:H/TiC/TiCN/TiN, was deposited on cemented tungsten carbide (WC-Co) substrate by an unbalanced magnetron sputtering system. Tribological characteristics of this coating were compared with the coatings of TiN, TiCN, and TiC/TiCN/TiN deposited on WC-Co substrates and the WC -Co substrate itself. The coating displayed excellent tribological properties, i.e., both low value and smooth curve of friction coefficient, and also, compared with the other tested materials, yielded the lowest wear depth when sliding against bronze under dry conditions. The coating thus protects against the high wear experienced when Ti-based coatings rub against copper alloy.